The invention is concerned with ultrasonic measuring systems and especially those that utilize an ultrasonic transducer for sending and receiving ultrasonic signals that are directed through a volume of liquid in a container to measure the level of the liquid. More particularly, the invention relates to a housing for the transducer assembly and related components, all of which must be located in a sealed enclosure to be emersed in the liquid.
Ultrasonic measuring systems are commonly used to measure the level of liquid in containers such as fixed storage tanks, fuel storage reservoirs and aircraft fuel tanks. These systems generally use a tubular probe or stillwell inserted approximately vertically in the tank. An ultrasonic transducer transmits a sinusoidal acoustical pulse through the stillwell to the surface of the liquid. An echo returns from the surface of the liquid to the transducer and provides a sinusoidal echo signal. A receiver responds to the echo signal and the total elapsed time is then determined. Thus, further data is calculated for display.
In these systems, a transducer assembly containing a piezoelectric crystal is usually connected to the stillwell at or near the bottom of the tank. Accordingly, the various components should be mounted in a sealed enclosure to prevent intrusion of liquid. Also, it is necessary to provide a means to pass a cable through the sealed enclosure to provide electrical current for the piezoelectric crystal.
One problem with these types of systems is that of eliminating the effects of electromagnetic interference (EMI) that could adversely effect the measurements obtained by the device.
Still another problem is that of securing the enclosure that contains the piezoelectric crystal and other components to the body of the stillwell at the desired location with the piezoelectric device positioned correctly at the end of the tube so as to direct the ultrasonic pulse along the axis of the stillwell.
The transducer enclosure of the present invention reduces the problems described above and affords other features and advantages heretofore not obtainable.